Proposing a Novel Approach to Design Horizontal Gas-liquid Separators

Surface separators play a very important role in oil and gas-producing fields. For this reason, their optimal design is very important for field applications. Semi-experimental design is a basic method to determine the dimensions of separators. Due to the simplifying assumptions used in semi-empirical design methods, they are only used for approximate estimation of the dimensions of the separators. The two-phase separator laboratory unit consists of a horizontal two-phase separator on a laboratory scale, pumps, compressors, and a static mixer to create a two-phase flow and a liquid filter to trap liquid droplets from the outlet gas flow. The separation efficiency is determined by weighing the trapped liquid droplets and by imaging the maximum diameter of the liquid droplets in the exhaust gas flow. In this research, the optimal dimensions of the separator are presented using a new combined method. In the proposed new combined method, CFD simulation of the two-phase separator was first carried out on a laboratory scale. Then the simulations were validated using laboratory data. Also, the optimal range for the slenderness ratio of the separator was determined. Finally, by using the new relationships presented in the form of dimensional analysis, the dimensions of the separator were determined, and then the performance of the designed two-phase separator was validated using the CFD simulation model. Validation results showed that the presented new method has a high capability in the design of gas-liquid separators. The relative error value between the results of the developed CFD model and the laboratory data was less than 7%. In order to use the presented new method in the field, the dimensions of the surface two-phase separator were determined for one of the production wells located in the South Pars gas field. One of the most important achievements of this research is providing the necessary platform for the optimal design and construction of surface separators for field use.